According to the letters, sent in 1956, Sir Martin Gilliat, the Queen Mother’s private secretary, wrote: “As far as food is concerned, Her Royal Highness has very catholic tastes but is not fond of either caviar or oysters.”

He added that she enjoyed drinking gin and tonic and whiskey and soda, and would rather have a glass of red or white wine than champagne. “Princess Margaret prefers meals to be as simple as possible and not to last too long. Three or four courses (including cheese or fruit) for lunch, and five for dinner are quite sufficient,” he added.

Sir Robert Scott, the governor of Mauritius at the time of the princess’s visit, was also informed that she did “not like motorcycle escorts”, and would accept gifts of books only from authors who were “of reputable character”.

According to the file, it appears the careful planning paid off: a message from Sir Martin to Sir Robert stated: “I am writing at the bidding of Princess Margaret to convey to you Her Royal Highness’ very real pleasure at the wonderful arrangements which were made for her visit to Mauritius.”

They reveal the Queen’s late sister also did not like tennis or golf, but would watch cricket or football.

Intimate details of royal dining habits are normally kept secret, but the letters were among a selection of colonial-era documents released by the National Archives.